Manual Section... (1) - page: envsubst

NAME

SYNOPSIS

DESCRIPTION

Operation mode:

-v, --variables

output the variables occurring in SHELL-FORMAT

Informative output:

-h, --help

display this help and exit

-V, --version

output version information and exit

In normal operation mode, standard input is copied to standard output,
with references to environment variables of the form $VARIABLE or ${VARIABLE}
being replaced with the corresponding values. If a SHELL-FORMAT is given,
only those environment variables that are referenced in SHELL-FORMAT are
substituted; otherwise all environment variables references occurring in
standard input are substituted.

When --variables is used, standard input is ignored, and the output consists
of the environment variables that are referenced in SHELL-FORMAT, one per line.